[wasm][asm.js] Check that property keys are literals for imports.

src/asmjs/asm-typer.cc

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/asmjs/asm-typer.h"
 
 #include <algorithm>
 #include <limits>
 #include <memory>
 #include <string>
@@ skipping 317 matching lines @@
         math[ii].standard_member);
     stdlib_math_types_[math[ii].name]->set_mutability(
         VariableInfo::kImmutableGlobal);
   }
 }
 
 // Used for 5.5 GlobalVariableTypeAnnotations
 AsmTyper::VariableInfo* AsmTyper::ImportLookup(Property* import) {
   auto* obj = import->obj();
   auto* key = import->key()->AsLiteral();
+  if (key == nullptr) {
+    return nullptr;
+  }
 
   ObjectTypeMap* stdlib = &stdlib_types_;
   if (auto* obj_as_property = obj->AsProperty()) {
     // This can only be stdlib.Math
     auto* math_name = obj_as_property->key()->AsLiteral();
     if (math_name == nullptr || !math_name->IsPropertyName()) {
       return nullptr;
     }
 
     if (!math_name->AsPropertyName()->IsUtf8EqualTo(CStrVector("Math"))) {
@@ skipping 2559 matching lines @@
     return true;
   }
 
   *error_message = typer.error_message();
   return false;
 }
 
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8